When you are converting a mach 1 from a 3650 to a t56 you must have these items
T56 Obviously lol T56 bell housing T56 drive shaft T56 trans mount T56 shifter And most importantly a GM lock out harness and that would be wired to your brake switch on the switch side. If you need further info feel free to contact me.
I have a mach 1 that I have converted and I drive everyday